This invention pertains to rollers, as for conveying tape, and the internal structure thereof.
The art has long required rotative rollers for defining a path for filamentary material; including paper tape, magnetic tape, and motion picture film.
At slow speeds of traverse and continuous motion of the tape a roller for the same may fulfill its function without being of critial design.
For modern tape-handling machines, having a rapid tape speed, as 500 to 2,000 centimeters per second, with frequent start-stop accelerations of the order of 20,000 cm per second per second, all elements of the dynamic chain become critical in design.
The mass of the roller adds undesirable inertia during the start-stop epochs. This is particularly true where axes of motion other than purely rotational are involved. Such axes are involved when the roller is mounted on a takeup arm.
Certain designs, such as those employing small ball bearings for journaling the roller upon its central shaft, have been both heavy and expensive. Another design, employing a very hard filled-type plastic, was found to audibly "squeal" at such a sound level after a few hours use that the roller could not be tolerated in commercial equipment manufactured for the competitive marketplace. Even specific alteration of the composition of the plastic to remove this disturbance was unsuccessful.
In the prior art literature, a roller coactive with a specialized reel for overcoming the propensity of Mylar plastic tape to straighten to a linear configuration rather than to be reeled has been fabricated in two halves. Each half has an inwardly beveled outer flange that spreads the sides of the reel to allow the tape to exit the reel. No aspects of cooling or freeing the roller of foreign material are disclosed.
The simple oil-conveying groove in known journals for machine shafts is well known. However, such grooves are restricted to the center of the journal, since the object is to distribute oil around the circumference of the journal, but not to provide a ready avenue of escape for the oil from the bearing. Such escape takes place slowly through the relatively tight fit of the shaft to the journal.
In deep-well in-well water pumps a helical groove extending the whole length of a stationary journal has been used for lubricating the journal by the flow of water through the groove when the shaft is rotating. This flow also removes sand or other foreign material found in well environments. The same type of journal may be used for the long shaft when the pump is down-well and the driving motor is at the surface.